Ok, I'll play. I'll sheepishly admit I had to looks some of these up to translate them to their English titles. And I feel a little bad that I haven't watched a lot of the others...I'd say "yet" but how do you all find the time???

winter
Ano Natsu de Matteru
Another
Brave10
Inu x Boku SS
Natsume Yuujinchou Shiedit: Ordinary life removed, second half of Chihayafuru's fall season was still airing then, but if that doesn't count feel free to skip it...
Nisemonogatari
Papa no In Koto o Kikinasai

i know for sure one of my top favorites from 2012 won't make it so ill just give it a shout out now. ginga e kickoff, its basically like little busters concept wise, but make sense and has that shonen feeling that makes a series successful. just that little kids playing soccer isn't for everyone.

Pocket Monsters: Best Wishes! Season 2 aired in Summer 2012
Chitose Get You!! is a series of shorts, which you've otherwise omitted
Uta Koi aired in Summer 2012
YuruYuri should be denoted as the second season
Nakaimo - My Sister is Among Them! aired in Summer 2012
Dog Days Season 2 aired in Summer 2012
Tanken Driland aired in Summer 2012
Horizon in the Middle of Nowhere should be denoted as the second season
Hakuouki should be Hakuouki Reimeiroku to distinguish if from similar series
Ebiten aired in Summer 2012